EXCLUSIVE: How They Caught Grim Sleeper Suspect Lonnie David Franklin Jr: His Own Son's DNA Trail Led Them Straight To Him

His own son's DNA trail led directly to Grim Sleeper suspect Lonnie David Franklin Jr.

Sources tell Los Angeles Weekly that the serial killer was caught through familial DNA testing after his son was arrested and had to give up a DNA swab.

A month ago, LAPD detective Dennis Kilcoyne said LAPD was going to try another controversial "familial DNA" matching probe, testing against 1 million samples in the California felon database to find the killer's cousin, brother or uncle.

"At least it brings a little bit of closure," Laverne Peters, the mother of victim Janecia Peters, told LA Weekly today. "It is very good news for me. I don't know whether to cry or scream."

The science of testing for familial DNA was hotly pursued by LAPD in 2008 when police realized that the Grim Sleeper sociopath, who had been slaughtering people since 1985, had kept his nose clean and stayed out of jail.

Because he'd stayed out of trouble, he'd never had his mouth swabbed for DNA.

No doubt, working with police every day as an LAPD mechanic, he knew every trick for avoiding arrest. He knew cop lingo and police habits.

But then, his son screwed up and apparently got nabbed by cops. His son got a mouth swab. His son's DNA test lit up like a Christmas tree:

His son's DNA, police tell LA Weekly, matched in so many ways that LAPD knew they'd found a close relative of Grim Sleeper, the most elusive serial killer to ever haunt the Western United States.

As the Weekly reported in 2008, an effort to scour the state of California's database of felons, in search of DNA that could turn up a close relative of the Grim Sleeper, and in turn lead to the elusive killer, turned up no family.

It was a big blow to LAPD's special Grim Sleeper task force, and to many in the community who had long awaited any new clues leading to his arrest.

But today, at long last, the nightmare appeared to be over.

Neighbors say the 51-year-old Franklin Jr. was a mechanic at the Los Angeles Police Department's 77th Division station, near where most of the killings occurred in the 1980's.

He was arrested at his house on 81st Street near Western Avenue in South Los Angeles today.

His home is almost at the epicenter of the troubled sector of Los Angeles where the brutal murders took place. Franklin is believed to have killed 11 people, mostly women, since 1985.

The killer, thought to have operated only in the 1980s, struck again in 2002, 2003 and 2007. He is the longest-operating serial killer west of the Mississippi and took a 13-year break before killing again. LA Weekly documented his return, and the police department's and City Hall's relative ambiguity over the case, in a 2008 story titled "Grim Sleeper Returns: He's Murdering Angelenos, as Cops Hunt his DNA."